Plants I'm Growing: Cactus "Scarlet Cup"

Once a year, fleetingly, the several varieties of cacti we have in pots on the deck give a good show. Perhaps my favorite among these is Echinocereus triglochidiatus, a type of hedgehog cactus known as scarlet cup, or claret cup, among other names. The flowers just began to open today. They will last perhaps over the weekend.--or maybe not that long.